1. Field of the Invention
The present invention relates to a prestressed concrete structure. More specifically, the invention relates to a prestressed concrete structure which, when PC steel members tightening a concrete molded article or tightening a plurality of concrete molded articles are broken, prevents the broken PC steel members from protruding or projecting outward beyond the side portions of the prestressed concrete structure.
2. Description of the Related Art
Prestressed concrete has heretofore been widely known. Prestressed concrete is a technology for enhancing the tensile load characteristics of the concrete by imparting a compressive load prior to the use, and is generally used for large concrete structures such as bridge structures. The compressive load can be imparted to the prestressed concrete in various ways. In a large concrete structure, the compressive load is often imparted relying on a pre-tension method, a post-tension method or a combination of the pre-tension method and the post-tension method.
In a large concrete structure and, particularly, the one adapted to the bridge structures, a plurality of tension members constituted by PC steel rods or PC steel wires that extend in a horizontally transverse direction perpendicular to the longitudinal direction of the bridges, are arranged in parallel in the horizontally longitudinal direction, so that a plurality of neighboring concrete molded articles are fastened together by these tension members, and a large tension is given to the tension members to tighten the concrete molded articles, in order to impart compressive load in the transverse direction to each of the concrete molded articles. In the thus formed concrete structure, in case a tension member to which a large tensile force is imparted breaks due to some cause, the broken tensile member protrudes or projects outward beyond the side portion of the concrete structure.
In order to solve this problem according to, for example, Japanese Patent No. 2742675, a reinforcing sheet of carbon fibers, aramid fibers or a combination thereof is adhered onto the axes of the PC steel members on the side surface of the prestressed concrete structure. In this reinforcing sheet, the warps and wefts are composed of fibers of the same material. When hit by the broken PC steel member, therefore, the reinforcing sheet peels roughly uniformly off the side surface of the prestressed concrete structure. When the reinforcing sheet is peeled up to the edges of the prestressed concrete structure, therefore, there results a conspicuous decrease in the adhesion strength of the reinforcing sheet on the side surface of the prestressed concrete structure. As described above, the reinforcing sheet is roughly uniformly peeled off the side surface of the prestressed concrete structure. When the prestressed concrete structure is a long one such as a bridge structure and has a side surface of an elongated shape, i.e., when the aspect ratio is relatively great, the peeling, which proceeds in a direction in parallel with the short side, quickly arrives at the edge of the prestressed concrete structure resulting in a remarkable drop in the adhesion strength of the reinforcing sheet.
The present invention was accomplished in order to solve this problem, and its object is to provide a prestressed concrete structure which, when the PC steel members used in the prestressed concrete structure are broken, prevents the broken PC steel members from protruding or projecting outward beyond the side portions of the prestressed concrete structure.
Another object of the present invention is to provide a fiber-reinforced resin composite material used for preventing the broken PC steel members from protruding or projecting outward beyond the side portions of the prestressed concrete structure.
A further object of the present invention is to provide a sheet member used for preventing the broken PC steel materials from protruding or projecting outward beyond the side portions of the prestressed concrete structure.